Plants are known for working plates of electronic circuits, for example wafers for the production of photovoltaic cells, which comprise at least a unit to deposit metal tracks on the plates and a positioning device that positions and transports the plates with respect to the deposition unit, and other possible work stations.
A positioning device is known, which comprises at least a feed belt to feed the plates and a rotating turret, or carousel, on which the plates fed by the feed belt are placed. The turret can be rotated at certain angles so as to transport and position each plate in defined operating positions of the deposition unit, so as to achieve the electronic circuits.
This type of transport member requires specific members to position the plates, which comprise at least a supporting plane mounted on the turret and on which the plate exiting the conveyor belt is initially deposited.
In order to guarantee the precision of the deposition of each metallic track on the plate, it is necessary to associate with the positioning device both a calibration and alignment station, to correct the position of the plate on the plane, and also a specific pick-up and discharge member, which moves the finished plates individually towards a discharge belt.
This entails a consequent increase both in production costs, and in the operating time of the plant, with an unavoidable reduction in productivity.
A positioning device is also known, wherein, instead of the supporting plane, a sliding belt is present on the turret, made of transpirant material, for example paper, wound between two winding/unwinding rollers.
This solution, even if it allows to guide the deposition of the plates on the turret, entails long maintenance steps and therefore inactivity of the plant, due to the need to control, each time, the efficiency of the paper strip after the treatment, and also to perform a periodical substitution of the paper strip, once this has been completely wound onto one of the rollers.
Furthermore, such maintenance steps are rather complex and require the intervention of particularly qualified personnel, or the use of sophisticated or particularly expensive equipment.
Plants for the treatment of plates are also known, in which the unit for the deposition of metal tracks acts by means of silk-screen printing with hot paste, or with cold paste.
In both known solutions, errors can occur, or smudges, in the deposition of the metallic tracks, mainly due to the relatively high differences in temperature between the printed paste and the surface of the plate.
In the state of the art, due to the high thermal gradient of the paste, difficulties or imperfections have also been found in the drying of the printed paste. This entails both incorrect prints and cracks or breaks that can interrupt or modify the correct conductivity of the printed tracks.
One purpose of the present invention is to achieve a positioning device of plates of electronic circuits, which is simple and economical to make and which allows a precise positioning of the plates on the transport member, without the need for long and costly steps of correcting the position of the plates.
Another purpose of the present invention is to achieve a device for positioning plates which does not require long, complex and costly maintenance steps for its replacement.
A further purpose of the present invention is to achieve a device for positioning plates that allows to limit to a minimum the possibility of errors, or smudges, in the deposition of the metal tracks, as well as the formation of cracks or breaks in the printed tracks during drying.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.